Printer and method adapted to reduce variability in ejected ink drop volume. A print head includes a plurality of nozzles integrally attached to the print head, each nozzle being capable of ejecting an ink droplet therefrom. At least one of the nozzles has an undesirable characteristic producing ink droplets of non-nominal volume. A waveform generator is connected to the nozzles for generating a plurality of waveforms to be supplied to the nozzles, so that the nozzles eject the ink droplets in response to the waveforms supplied thereto. Each waveforms has a plurality of pulses controlling ink droplet volume. A controller is provided for controlling the waveforms supplied to the nozzles and for transmitting the waveforms to the nozzles in order to eject the ink droplets so as to compensate for the non-nominal volume by controlling the number of pulses in the waveform. In this manner, all nozzles produce ink droplets of nominal volume regardless of physical or electrical variations between nozzles.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A pinter capable of reducing ink volume variability, comprising: (a) a print head; (b) at least one nozzle integrally attached to said print head, said nozzle having an ink chamber therein capable of ejecting a plurality of ink droplets therefrom, the chamber producing ink droplets each of a non-nominal volume; (c) a waveform generator connected to said nozzle for generating an electronic waveform to be supplied to said nozzle, so that said nozzle ejects the ink droplet in response to the waveform supplied thereto, the waveform being defined by an electronic waveform having a plurality of pulses controlling ink droplet volume; (d) a controller connected to said nozzle for transmitting the electronic waveform to said nozzle to eject the ink droplet so as to compensate for the non-nominal volume by controlling the number of pulses in the waveform, so that the at least one chamber produces an ink droplet of nominal volume; and (e) a look-up table associated with said nozzle for storing values of number of pulses associated with said nozzle.
2. The apparatus of claim 1 , wherein said look-up table has a plurality of pulses defining each waveform.
3. The apparatus of claim 2 , further comprising a nozzle selector interconnecting said waveform generator and said print head for selecting said nozzle for activation.
4. The apparatus of claim 1 , further comprising an electromechanical transducer disposed in said nozzle and responsive to said waveform for ejecting the ink drop from said nozzle.
5. The apparatus of claim 4 , wherein said electromechanical transducer is formed of a piezoelectric material.
6. A printer capable of reducing ink volume variability for gray-scale printing on a receiver medium, comprising: (a) a print head; (b) a plurality of nozzles integrally attached to said print head, each of said nozzles capable of ejecting an ink droplet therefrom, at least one of the nozzles producing ink droplets each of non-nominal volume; (c) a waveform generator connected to said nozzles for generating a plurality of waveforms supplied to said nozzles, so that said nozzles eject the ink droplets in response to the waveforms supplied thereto, each of said waveforms having a plurality of pulses controlling ink droplet volume; (d) a look-up table connected to said nozzles for storing values of number of pulses to be supplied to each nozzle; (e) a calibrator in communication with said look-up table for converting an input image file having a plurality of pixels to a calibrated image file, the input image file including a plurality of pixel values for each pixel of the input image file; (f) an image halftoning unit connected to said image calibrator for halftoning the calibrated image file to generate a halftoned image file having the plurality of pixel values; (g) a nozzle selector interconnecting said waveform generator and said print head for selecting predetermined ones of said nozzles for actuation; (h) a controller connected to said image halftoning unit and said nozzle selector for controlling the waveforms supplied to said nozzles and for transmitting the electronic waveforms to said nozzles to eject the ink droplets by controlling the number of pulses in the respective waveform, so that the at least one chamber produces ink droplets each of nominal volume; and (i) a piezoelectric electromechanical transducer disposed in at least one of said nozzles and responsive to said waveform for ejecting the ink droplet from said nozzle.
7. A method of reducing variability in ejected ink drop volume, comprising the steps of: (a) providing a print head having at least one nozzle, the nozzle having an ink chamber therein capable of ejecting ink droplets therefrom, the chamber producing ink droplets each of non-nominal volume; (b) operating a waveforn generator and generating at electronic waveform supplied to the nozzle, so that the nozzle ejects the ink droplet in response to the waveform supplied thereto, the waveform having a plurality of pulses controlling ink droplet volume; (c) transmittinig the electronic waveformn to the nozzle to eject the ink droplet by controlling the number of pulses in the waveform, so that the chamber produces ink droplets each of nominal volume; and (d) using a look-up table that stores values of number of pulses to be supplied to the nozzle.
8. The apparatus of claim 7 , wherein in the step of using a look-up table the look-up table defines a plurality of pulses for each electronic waveform.
9. The apparatus of claim 8 , further comprising the step of selecting the nozzle for activation by using a nozzle selector interconnecting the waveform generator and the nozzle.
10. The apparatus of claim 8 , wherein an electromechanical transducer is disposed in the nozzle and responsive to the waveform for ejecting the ink droplet from the nozzle.
11. The apparatus of claim 10 , wherein the electromechanical traducer is formed of a piezoelectric material.
12. A method of reducing ink volume variability for gray-scale printing on a receiver medium, comprising the steps of: (a) providing a print head having a plurality of nozzles, each of the nozzles capable of ejecting ink droplets therefrom, at least one of the nozzles having been determined to produce ink droplets each of non-nominal volume; (b) generating a plurality of waveforms supplied to the nozzles, so that the nozzles eject the ink droplets in response to the respective waveforms supplied thereto, each of the waveforms having a plurality of pulses controlling ink droplet volume; (c) providing a look-up table that stores data values of number of pulses for each nozzle; (d) using a calibrator in communication with the look-up table to convert an input image file having a plurality of pixels to a calibrated image file, the input image file including pixel value data representing multiple levels of tones greater than two for each pixel of the input image file; (e) operating upon the calibrated image file to generate a halftoned image file having pixel value data representing multiple levels of tones greater than two for each pixel of the input image file; (f) selecting the nozzles for activations; (g) using the halftoned image file and the data values stored in the look-up table to determine the waveforms supplied to the nozzles and transmitting the electronic waveforms to the nozzles to eject the ink droplets by controlling the number of pulses in each waveform, so that the at least one nozzle produces ink droplets each of nominal volume; and (h) operating an electromechanical transducer in the at least one nozzle, the electromechanical transducer being responsive to the waveform for ejecting the ink droplet from the nozzle.
13. The method of claim 12 and wherein the look-up table provides for each of plural droplet volumes a printing parameter to be recorded by the at least one nozzle.
14. The method of claim 13 and wherein in addition to number of pulses the printing parameter in the look-up table includes at least one other from the group consisting of printing start time after a start of line printing time, pulse-width, voltage pulse amplitude, and delay time interval between pulses.
15. The method of claim 14 and wherein the transducer is a piezoelectric transducer.
16. The method of claim 13 and wherein the transducer is a piezoelectric transducer.
17. The method of claim 12 and wherein the transducer is a piezoelectric transducer.
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June 12, 1998
August 6, 2002
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